Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 3,606	$ 3,804	$ 1,213
Defined benefit postretirement and post-employment plans:
Actuarial changes, net of tax of $14, $17 and $69, respectively	75	29	115
Prior service costs, net of tax of $12, ($16) and ($18), respectively	8	(26)	(31)
Other, net of tax of $1, $0 and $0, respectively	4	0	0
Other comprehensive income	87	3	84
Comprehensive income	3,693	3,807	1,297
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	75	65	41
Noncontrolling interests	751	307	(2)
Comprehensive income attributable to MPC	$ 2,867	$ 3,435	$ 1,258